In a principal aspect the present invention relates to the construction of stabilized soil or reinforced earth structures. This building technique is commonly used to produce structures such as retaining walls, bridge abutments, etc.
A stabilized soil structure combines a compacted fill, a facing, and reinforcements usually connected to the facing. The reinforcements are placed in the soil with a density dependent on the stresses that might be exerted on the structure, the thrust forces of the soil being reacted by the soil-reinforcements friction.
The invention more particularly concerns the case where the reinforcements are in the form of strips of synthetic material, for example based on polyester fibres.
The facing is most often made up of prefabricated concrete elements, in the form of slabs or blocks, juxtaposed to cover the front face of the structure. There may be horizontal steps on this front face between different levels of the facing, when the structure has one or more terraces.
The reinforcements placed in the fill are usually secured to the facing by mechanical connecting members that may take various forms. Once the structure is complete, the reinforcements distributed through the fill transmit high loads, in some cases of up to several tonnes. Their connection to the facing needs to be robust in order to maintain the cohesion of the whole.
The connecting members exhibit risks of degradation. They are often sensitive to corrosion due to moisture or to chemical agents which are present in or which have infiltrated into the fill. The connecting members are sometimes made on the basis of resins or composite materials so that they corrode less readily. However, their cost is then increased, and it is difficult to give them good mechanical properties. It is therefore desirable to be able to dispense with connecting members between the facing element and the reinforcements of the structure.
In some systems, the facing elements are configured in such a way as to present at least one passage intended to receive a reinforcement strip.
In U.S. Pat. No. 5,839,855, the passage is in the shape of a C within the thickness of the facing element in the form of a panel. When the strip is put in place, its two sections emerging from the facing element are located in two parallel horizontal planes offset in the vertical direction. This condition of emergence of the strips from the panel is not ideal because it makes it necessary to increase the number of filling and compacting operations, which complicates and prolongs the implementation of the work. This does not easily permit homogeneous tensioning of the strips, because the strip is not retained by the panel when its lower portion is covered with fill.
For these reasons, it is generally desirable for the strips to emerge from the facing element in the same horizontal plane.
In addition, the C-shaped path of the reinforcement strips is not optimal in terms of the robustness of the anchoring when stressed. The curve of the path near the point of emergence of the strip weakens its anchoring to the element because it causes working in tension of a small thickness of concrete, which is not a good way of stressing this material.
A similar problem arises with a facing element of the type described in FR-A-2 812 893. This element also has a pre-formed path in the shape of a C. In addition, this C-shaped path is arranged so that each portion of the reinforcement strip emerges from the element oriented in a vertical plane. This is unsatisfactory because the strip placed on the ground positions itself naturally in a horizontal plane, so that each portion of the strip in the fill twists one quarter of a turn. Such twisting is unfavourable in terms of the mechanical behaviour of the reinforcement.
It is an object of the present invention to propose a novel method of anchoring reinforcement strips to a facing of a stabilized soil structure, making it possible to reduce the incidence of the problems set out above.